1. Field of the Invention
The present invention relates to a stereoscopic image display device, and more particularly, to a stereoscopic image display device which enables multiple viewers to observe a stereoscopic image without use of glasses, and particularly to observe the stereoscopic image through detection of movement of the viewers even when the viewers change positions.
2. Discussion of the Related Art
These days, it is expected that services to achieve high speed data transmission to be established based on high speed data communication networks are developed from a simply listening and speaking service, such as a current phone, toward a watching and listening service, i.e., a multimedia service through a digital terminal processing character, voice, and image data at high speed, and is expected to be eventually developed toward a hyperspace-type real three-dimensional data communication service, i.e., a realistically and three-dimensionally watching, feeling, and enjoying service beyond time and space.
In general, three-dimensional stereoscopic imagery is achieved based upon the principle of stereo vision through two eyes. Since there is an interval of approximately 65 mm, between two eyes, the left eye and the right eye perceive slightly different images due to the positional difference between the two eyes. Such an image difference due to the positional difference therebetween is referred to as binocular disparity.
A three-dimensional stereoscopic image display device enables the left eye to observe only an image corresponding to the left eye and the right eye to observe only an image corresponding to the right eye using the binocular disparity, thus enabling a viewer to feel three-dimensional effect. That is, the left/right eyes respectively observe different two-dimensional images, and when the two images are transferred to a brain through retinas, the brain correctly combines the two images and reproduces depth perception and realism of an original three-dimensional image. Such ability is usually referred to as stereography (stereoscopy), and a display device to which stereography is applied is referred to as a stereoscopic image display device.
Stereoscopic image display devices are divided into a glasses type and an autostereoscopic type according to whether or not glasses are required. Further, autostereoscopic type display devices are divided into a lenticular type and a switchable panel type according to shapes of structures implementing three-dimensional images.
A lenticular type stereoscopic image display device includes a semi-cylindrical lenticular sheet attached to a display panel and thus implements a stereoscopic image. A switchable panel type stereoscopic image display device includes a switchable panel provided on a display panel emitting two-dimensional images to convert the two-dimensional images into a three-dimensional image and thus implements a stereoscopic image. Switchable panel type stereoscopic image display devices are divided into a switchable barrier type and a switchable liquid crystal lens type.
FIG. 1 is a view illustrating a general switchable barrier type stereoscopic image display device.
As shown in FIG. 1, a barrier 10 and a slit 15 are alternately arranged in front of a display panel 5 having right eye image information R and left eye image information L corresponding to a right eye RE and a left eye LE of a viewer, and thus the right eye image information R is input to the right eye RE of the viewer and the left eye image information L is input to the left eye LE of the viewer through the slit 15. As described above, a region in which the right eye image information R is input to the right eye RE of the viewer and the left eye image information L is input to the left eye LE of the viewer is referred to as an ortho-stereoscopic region.
In case of the above general switchable barrier type stereoscopic image display device having two views (disparity), even if a viewer moves slightly, the viewer moves to an inverse-stereoscopic region in which the left eye image information L is input to the right eye RE of the viewer and the right eye image information R is input to the left eye LE of the viewer, and thus cannot observe the stereoscopic image.